Thermal imaging device and method

A thermal imaging device (10) includes a rotational scanning mirror (32) scanning a viewed scene across a linear detector array (50) including plural spaced apart detector elements (50', 50'', 50''', . . . ). The scanner includes an annular magnetic track (174) carried on the rotational scanning mirror (32), and a stationary reading head (178) responding to passage of magnetic domains (176) on the magnetic track (174) to commutate position of the rotational scanning mirror (32). The reading head (178) includes pairs of magneto-resistive elements (182) which are physically positioned relative to one another and are electrically connected so as to be simultaneously exposed to respective magnetic flux maxima and magnetic flux minima as the scanner mirror (32) rotates. As a result, domain-to-domain variations of flux intensity of the magnetic domains (176) on the magnetic track (174) are averaged out. Consequently, a much improved quality of commutation signal results, with improved timing correspondence of the rotational position and speed of the scanning mirror to the requirements of the thermal imaging device (10).